Function raise_py_error

LeanPy/native/python_bridge.c:271–303

If a Python exception is set, fetch a string for it, clear, and return * a Lean IO error result. Caller transfers ownership. */

/* If a Python exception is set, fetch a string for it, clear, and return
 * a Lean IO error result. Caller transfers ownership. */
static lean_object *raise_py_error(void) {
    PyObject *etype = NULL, *evalue = NULL, *etb = NULL;
    p_PyErr_Fetch(&etype, &evalue, &etb);
    p_PyErr_NormalizeException(&etype, &evalue, &etb);
    char buf[1024];
    const char *etname = "PythonError";
    const char *emsg = "";
    PyObject *s = NULL, *tn = NULL;
    if (evalue) {
        s = p_PyObject_Str(evalue);
        if (s) {
            const char *cs = p_PyUnicode_AsUTF8(s);
            if (cs) emsg = cs;
        }
        if (etype) {
            tn = p_PyObject_GetAttrString(etype, "__name__");
            if (tn) {
                const char *cn = p_PyUnicode_AsUTF8(tn);
                if (cn) etname = cn;
            }
        }
        snprintf(buf, sizeof(buf), "%s: %s", etname, emsg);
        /* DecRef after snprintf: etname/emsg point into s/tn internals. */
        if (tn) p_Py_DecRef(tn);
        if (s)  p_Py_DecRef(s);
    } else {
        snprintf(buf, sizeof(buf), "Python error (no value)");
    }
    if (etype)  p_Py_DecRef(etype);
    if (evalue) p_Py_DecRef(evalue);
    if (etb)    p_Py_DecRef(etb);
    return raise_io_error(buf);
}

/* Wrap an owned PyObject as IO Py; if NULL, propagate any pending Py error. */
static lean_object *ok_owned_or_err(PyObject *o) {